Use the WHEN clause to specify the topics and the number of events required for each topic.
For example, the following clause looks for one stock event:
WHEN 1 stock
The following clause looks for five stock events
s
and one news event
n
:
WHEN 5 stock s, 1 news n
While creating a rule, if you do not specify the number for the topic in the WHEN clause , you receive an alert to specify the number of topics. If you proceed without specifying a number, the rule will look for all events for the specified topic.